Figure 1: Dependence of the magnetic transition temperatures TN1 and TN2 with the cooling rate.
From: Tuning magnetic spirals beyond room temperature with chemical disorder
(a) Crystal structure of YBaCuFeO5 showing the Cu/Fe disorder in the bipyramidal sites. (b,c) Magnetic structures in the commensurate collinear (b) and incommensurate spiral phases (c). In both cases, only ¼ of the magnetic unit cell is shown. The rotation plane of the spiral is indicated for clarity. The nearest-neighbour magnetic couplings along the c crystal axis are also shown. (d) Mass magnetic susceptibility M/H as a function of temperature measured under the application of an external magnetic field of 5,000 Oe for the five YBaCuFeO5 powder samples prepared using different cooling rates in the last annealing. (e) Contour maps showing the temperature dependence of the position and the intensities of the magnetic Bragg reflection (½ ½ ½) associated to the high-temperature collinear antiferromagnetic phase, and the (½ ½ ½ ± q) satellites of the low-temperature magnetic spiral phase for the five samples. The measurements were performed by heating at the neutron powder diffractometer DMC (SINQ, Switzerland) using a wavelength λ=4.5 Å. The blue and red arrows indicate, respectively, the magnetic transition temperatures TN1 and TN2. (f) Stability range of the collinear and spiral phases with the cooling rate. Dashed lines are guides for the eye.
